Now, we compare the observables of two models with each other and with observations. The typical energy scale of inflation is \(M\simeq 10^{15}\)  GeV and assuming that \(m\simeq 10^{18}\)  GeV, we can find the value of \(M_5\)  by demanding that the result in Eq. REF  match the observed value \(A_s^{Planck}\sim 2.0989\times 10^{-9}\)  [1]}. It is found that \(M_5\)  is typically of order \(M_5\sim 10^{16}\)  GeV (it depends only weakly on \(n\)  and \(N\) ); this is consistent with a previously found lower bound of \(M_5\)  of order \(10^9\)  GeV [2]} There can also exist an upper bound if one wants to use the model to address other problems such as baryogenesis [3]} but we will not consider it here. . So, we find the results in Table REF . From Table REF , we see that the RS2 model predicts larger tensor-to-scalar ratio than the 4D case. This is also an expected feature of inflation in RS2 model (for example, in Ref. [2]} it was found that tensor-to-scalar ratio in RS2 model is larger than that in 4D spacetime for the concave inflaton potential of the form \(V\sim \phi ^n\)  with \(0<n<1\) ).
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